js-on-sx: 10 new Object.* globals (getPrototypeOf, create, is, hasOwn, defineProperty, ...)

Extends the Object global dict with:
- getPrototypeOf / setPrototypeOf — read/write __proto__ chain
- create(proto, props?) — builds new obj with proto and optional descriptors
- defineProperty / defineProperties — descriptor.value only (no getters/setters)
- getOwnPropertyNames / getOwnPropertyDescriptor(s) — simple shapes
- isExtensible / isFrozen / isSealed (permissive stubs)
- seal / preventExtensions (no-ops)
- is — SameValue (NaN is NaN, -0 vs +0 distinguished via inspect string)
- fromEntries — inverse of entries
- hasOwn — explicit owner check for string keys

9 new unit tests, 506/508 total.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/js/test.sh

@@ -1213,6 +1213,26 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 3709)
 (eval "(js-eval \"var a=[1,2,3]; a.keys().join(',')\")")
 
+;; ── Phase 11.objglobal: Object.getPrototypeOf, .create, .is, .hasOwn etc. ──
+(epoch 3900)
+(eval "(js-eval \"var o = Object.create(null); o.x=5; o.x\")")
+(epoch 3901)
+(eval "(js-eval \"Object.is(NaN, NaN)\")")
+(epoch 3902)
+(eval "(js-eval \"Object.is(0, 0)\")")
+(epoch 3903)
+(eval "(js-eval \"Object.hasOwn({a:1}, 'a')\")")
+(epoch 3904)
+(eval "(js-eval \"Object.hasOwn({a:1}, 'b')\")")
+(epoch 3905)
+(eval "(js-eval \"Object.fromEntries([['a',1],['b',2]]).a\")")
+(epoch 3906)
+(eval "(js-eval \"var o = {a:1}; Object.defineProperty(o,'b',{value:42}); o.b\")")
+(epoch 3907)
+(eval "(js-eval \"var o = {a:1}; Object.getOwnPropertyNames(o).length\")")
+(epoch 3908)
+(eval "(js-eval \"Object.isExtensible({})\")")
+
 ;; ── Phase 11.globals: NaN / Infinity / strict-eq ─────────────
 (epoch 3750)
 (eval "(js-eval \"typeof NaN\")")
@@ -1927,6 +1947,17 @@ check 3707 "arr.toReversed"                '"2,1,3"'
 check 3708 "arr.toSorted"                  '"1,1,3,4,5"'
 check 3709 "arr.keys"                      '"0,1,2"'
 
+# ── Phase 11.objglobal: Object.getPrototypeOf, .create, .is, .hasOwn ──
+check 3900 "Object.create(null)"           '5'
+check 3901 "Object.is(NaN,NaN)"            'true'
+check 3902 "Object.is(0,0)"                'true'
+check 3903 "Object.hasOwn a"               'true'
+check 3904 "Object.hasOwn missing"         'false'
+check 3905 "Object.fromEntries"            '1'
+check 3906 "Object.defineProperty"         '42'
+check 3907 "Object.getOwnPropertyNames"    '1'
+check 3908 "Object.isExtensible"           'true'
+
 # ── Phase 11.globals: NaN / Infinity / strict-eq ─────────────
 check 3750 "typeof NaN"                    '"number"'
 check 3751 "isNaN(NaN)"                    'true'